The UK's longest-serving prisoner has died in jail, 55 years after he was convicted of murdering a five-year-old.

John Straffen, from Bath, was 22 when he was found guilty on 25 July 1952 of murdering schoolgirl Linda Bowyer.

Straffen, who was 77 when he died, was sentenced to death, though that was later reduced to life imprisonment.

He had previously appeared at Somerset Assizes in October 1951 charged with the murders of Cicely Batstone, nine, and six-year-old Brenda Goddard.

The Ministry of Justice said he died in the healthcare unit at Frankland Prison in County Durham following an illness.

Unfit to plead

He was sent to Broadmoor high-security hospital after being found unfit to stand trial but escaped on April 29 1952 for four hours. Linda Bowyer's body was found the following morning.

His solicitors said: "He had been declared a 'mental defective' in 1947 and committed to a 'colony for mental defectives'."

Sir David Maxwell Fyfe, the then home secretary, reduced Straffen's sentence on the grounds that he was a "feeble-minded person".

Birmingham-based firm Hadgkiss Hughes & Beale said in 2001 that an "eminent" forensic psychiatrist, who was unnamed, had re-examined original pre-trial reports on Straffen and said he was not fit to be tried.

If he was unfit to plead in 1951, he could not have effectively taken part in a trial nine months later, they said.

After Straffen's escape from Broadmoor in 1952, a siren system was installed to alert local residents if an inmate was on the loose.

The alarm is tested every Monday morning, sending its distinctive howl echoing around the villages of the Berkshire commuter belt.